Pulse event detection is common among electronic systems. It can be performed by synchronous or asynchronous methods depending on the requirement of the system. The asynchronous method detects pulses, without the use of a clock and is suited for low power operations of a mouse button or keyboard events, for example. However, in the operation of a typical asynchronous event detection, shown in FIG. 1, the event pulse might be missed depending on the frequency of the events.
For example, when a rising edge event is latched in latch 10, it triggers an interrupt 13 to a processor. After, being interrupted, the processor typically clears the event latched in latch 10 by writing to a memory location. The write operation to the memory by the processor generates a low going pulse at 12 and asynchronously clears the latch 10. The problem arises when there is an incoming rising edge next event during this interrupt-driven clear cycle.
For example, after the pulse event is acknowledged and processed by a control unit of the system (e.g., a processor), the detection circuit has to be cleared and re-armed for detection of next event. It is likely that the clearing of the detection circuit masks a new incoming edge event. This causes the new incoming event to be missed and lost.
Therefore, there is a need for an circuit and method for a more reliable pulse event detection.